MaximumYield explains Cell wall

The structure of a cell wall differs according to various plants. For example, in dandelions and redwood trees, cell walls are located on the outsides of the cells. Each plant has its own set of cell walls that has been especially conceived to meet the needs of the individual tree or flower. Consequently, the redwood is equipped with a rigid cell wall to prevent it from toppling over during storms while maintaining its impressive height.

Cell walls also act as a defense mechanism for plants. For example, flowers tend to droop when dehydrated but as soon as they are watered the cell walls cause them to become more rigid again. Cell walls also have a role to play if flowers are overwatered; in these cases, the cell walls protect the cells from the over-expansion that may occur due to too much water.

Cell walls also contain tiny holes known as plasmodesmata that enable nutrients to enter the plant. These holes are also shaped to allow waste to exit the plants.